Aromatic polyamide fibers and method of printing such fibers with acid dyes in the presence of hexamethylene diamine dihydrochloride impregnated in fiber

Abstract

A diamine salt and a surfactant are imbibed into never-dried aromatic polyamide fibers which may be printed or overprinted with acid dyes, after drying.

We claim: 
     
       1. Poly(meta-phenylene isophthalamide) fibers adapted to be printed with an acid dye and containing an acid dye, a diamine salt and a surfactant, wherein the diamine salt is hexamethylenediamine dihydrochloride and wherein such fibers contain from about 0.3 to 3 wt. % of such diamine salt, and   wherein such fibers contain from about 5 to 15 wt. % of the surfactant and wherein such surfactant is cationic.   
     
     
       2. Poly(meta-phenylene isophthalamide) fibers adapted to be overprinted with acid dyes and containing a surfactant, a dye, a diamine salt and an ultraviolet light screener, wherein the diamine salt is hexamethylenediamine dihydrochloride and wherein such fibers contain at least 0.3 to 3 wt. % of the diamine salt,   wherein such fibers contain from about 5 to 15 wt. % of the surfactant and wherein such surfactant is cationic,   wherein such fibers contain from about 1 to 5 wt. % of the ultraviolet screener, and   wherein such fibers contain from about 0.5 to 5 wt. % of a first acid dye prior to being overprinted with at least a second acid dye.   
     
     
       3. Poly(meta-phenylene isophthalamide) fibers containing a cationic surfactant, an acid dye and a hexamethylenediamine dihydrochloride diamine salt, such fibers being overprinted with at least another acid dye. 
     
     
       4. A method of printing poly(meta-phenylene isophthalamide) fibers including the steps of imbibing a diamine salt, a cationic surfactant and an acid dye into the never-dried fibers, using steam; drying the fibers; and thereafter printing such dried fibers with another acid dye and wherein the diamine salt is hexamethylenediamine dihydrochloride. 
     
     
       5. A method of printing poly-(meta-phenylene isophthalamide) fibers including the steps of simultaneously imbibing a surfactant, a diamine salt, an acid dye, and an ultraviolet light screener into never-dried aromatic polyamide fibers, using steam; drying the fibers; and thereafter printing such fibers with another acid dye, wherein the diamine salt is hexamethylenediamine dihydrochloride and wherein such fibers contain from about 0.3 to 3 wt. % of such diamine salt after drying,   wherein such fibers contain from about 5 to 15 wt. % of the surfactant after drying and wherein such surfactant is cationic and   wherein such fibers contain from about 1 to 6 wt. % of the ultraviolet screener after drying.   
     
     
       6. A method of overprinting poly(meta-phenylene isophthalamide) fibers including the steps of combibing, in a single step, a cationic surfactant, diamine salt, an ultraviolet light screener and a first acid dye into never-dried aromatic polyamide fibers, using steam; drying the fibers; and thereafter overprinting such fibers with at least a second acid dye and wherein the diamine salt is hexamethylenediamine dihydrochloride. 
     
     
       7. A method of overprinting aromatic polyamide fibers including the steps of padding onto the surface of never-dried aromatic poly(m-phenylene isophthalamide) fibers an aqueous mixture including   a cationic surfactant, a diamine salt, an ultraviolet light screener and a first acid dye   heating the fibers with steam to imbibe these materials into the fibers;   drying the fibers; and   thereafter overprinting such fibers with at least a second acid dye, and wherein the diamine salt is hexamethylenediamine dihydrochloride.   
     
     
       8. The method of claim 7 wherein such aqueous mixture includes a mixture of acid dyes which -are imbibed into the fibers prior to drying. 
     
     
       9. The method of claim 8 wherein such fibers are over-printed with at least two acid dyes after drying. 
     
     
       10. The method of claim 8 wherein the dried fibers are formed into fabric having a background color due to the presence of the imbibed acid dye and wherein such fabric is overprinted with at least two acid dyes to form the other colors of a camouflage material.